Re-structure sat-rs

- Add new shared subcrate satrs-shared to split off some shared
  components not expected to change very often.
- Renmame `satrs-core` to `satrs`. It is expected that sat-rs will remain
  the primary crate, so the core information is superfluous, and core also
  implies stability, which will not be the case for some time.

satrs/src/cfdp/user.rs

@@ -0,0 +1,96 @@
+use spacepackets::{
+    cfdp::{
+        pdu::{
+            file_data::SegmentMetadata,
+            finished::{DeliveryCode, FileStatus},
+        },
+        tlv::{msg_to_user::MsgToUserTlv, WritableTlv},
+        ConditionCode,
+    },
+    util::UnsignedByteField,
+};
+
+use super::TransactionId;
+
+#[derive(Debug, Copy, Clone)]
+pub struct TransactionFinishedParams {
+    pub id: TransactionId,
+    pub condition_code: ConditionCode,
+    pub delivery_code: DeliveryCode,
+    pub file_status: FileStatus,
+}
+
+#[derive(Debug)]
+pub struct MetadataReceivedParams<'src_file, 'dest_file, 'msgs_to_user> {
+    pub id: TransactionId,
+    pub source_id: UnsignedByteField,
+    pub file_size: u64,
+    pub src_file_name: &'src_file str,
+    pub dest_file_name: &'dest_file str,
+    pub msgs_to_user: &'msgs_to_user [MsgToUserTlv<'msgs_to_user>],
+}
+
+#[cfg(feature = "alloc")]
+#[derive(Debug)]
+pub struct OwnedMetadataRecvdParams {
+    pub id: TransactionId,
+    pub source_id: UnsignedByteField,
+    pub file_size: u64,
+    pub src_file_name: alloc::string::String,
+    pub dest_file_name: alloc::string::String,
+    pub msgs_to_user: alloc::vec::Vec<alloc::vec::Vec<u8>>,
+}
+
+#[cfg(feature = "alloc")]
+impl From<MetadataReceivedParams<'_, '_, '_>> for OwnedMetadataRecvdParams {
+    fn from(value: MetadataReceivedParams) -> Self {
+        Self::from(&value)
+    }
+}
+
+#[cfg(feature = "alloc")]
+impl From<&MetadataReceivedParams<'_, '_, '_>> for OwnedMetadataRecvdParams {
+    fn from(value: &MetadataReceivedParams) -> Self {
+        Self {
+            id: value.id,
+            source_id: value.source_id,
+            file_size: value.file_size,
+            src_file_name: value.src_file_name.into(),
+            dest_file_name: value.dest_file_name.into(),
+            msgs_to_user: value.msgs_to_user.iter().map(|tlv| tlv.to_vec()).collect(),
+        }
+    }
+}
+
+#[derive(Debug)]
+pub struct FileSegmentRecvdParams<'seg_meta> {
+    pub id: TransactionId,
+    pub offset: u64,
+    pub length: usize,
+    pub segment_metadata: Option<&'seg_meta SegmentMetadata<'seg_meta>>,
+}
+
+pub trait CfdpUser {
+    fn transaction_indication(&mut self, id: &TransactionId);
+    fn eof_sent_indication(&mut self, id: &TransactionId);
+    fn transaction_finished_indication(&mut self, finished_params: &TransactionFinishedParams);
+    fn metadata_recvd_indication(&mut self, md_recvd_params: &MetadataReceivedParams);
+    fn file_segment_recvd_indication(&mut self, segment_recvd_params: &FileSegmentRecvdParams);
+    // TODO: The standard does not strictly specify how the report information looks..
+    fn report_indication(&mut self, id: &TransactionId);
+    fn suspended_indication(&mut self, id: &TransactionId, condition_code: ConditionCode);
+    fn resumed_indication(&mut self, id: &TransactionId, progress: u64);
+    fn fault_indication(
+        &mut self,
+        id: &TransactionId,
+        condition_code: ConditionCode,
+        progress: u64,
+    );
+    fn abandoned_indication(
+        &mut self,
+        id: &TransactionId,
+        condition_code: ConditionCode,
+        progress: u64,
+    );
+    fn eof_recvd_indication(&mut self, id: &TransactionId);
+}